As omnivores, young children learn what they like to eat, when to eat and how much to eat. The research proposed investigates the contributions made by learning and experience to the development of food intake regulation during early childhood. The focus of the proposed project is on the role of associative conditioning in the acquisition of preferences for high fat foods. Currently there is widespread concern that the percentage of total energy from dietary fat is too high and must be reduced to reduce the incidence of obesity and chronic disease. However, reductions in dietary fat intake have proved difficult to effect, largely because fat tastes good. But why? Unlike the sweet taste, there is no unitary fat taste, and no innate preference for fat. In fact, most of us are very bad at detecting fat in food, probably because the characteristics that fat imparts differ from one food to the next: crunchiness, flakiness, tenderness, creaminess, and greasiness are all characteristic of fat in foods. The lack of a unitary fat taste and the absence of evidence for an innate preference for fat are consistent with the idea that preferences for high fat foods are learned. Children are sensitive to the carbohydrate content of foods in controlling their food intake, and learn to prefer foods high in carbohydrate (and hence energy density) relative to those low in energy density. To date, human data for conditioned food preferences are limited to carbohydrate because the carbohydrate manipulations are readily and quickly sensed. However, fat has 9 kcal/gm for carbohydrate, and most of the variance in the energy content of foods is attributable to differences in fat content. Given the powerful contribution made by fat to total energy intake, it is important to determine whether preferences for high fat foods are a result of conditioning. We propose to apply the conditioning protocols developed in the previous funding period to investigate the contributions of associative conditioning to preferences for high fat foods. Research will investigate: 1) children's responsiveness to differences in fat content and energy density in modulating food intake and 2) whether differences in fat content can serve as unconditioned stimuli in associative conditioning of food preferences and conditioned satiety. We will also begin to investigate the stability of individual differences in responsiveness to fat content and energy density in controlling food intake, and familial correlates of these differences. The introduction of fat substitutes into the food supply makes conducting this research more relevant and more feasible. The results will contribute to the knowledge base for the development of intervention strategies needed to meet current dietary guidelines, which call for reducing dietary fat intake.